kern.features.linux: 1 meaning linux 32 bits binaries are supported
kern.features.linux64: 1 meaning linux 64 bits binaries are supported
The goal here is to help 3rd party applications (including ports) to determine
if the host do support linux emulation
Reviewed by: dchagin
MFC after: 1 week
Relnotes: yes
Differential Revision: D5830